The present invention relates to a rubber-containing resin composition and a styrene resin composition containing the rubber-containing resin composition. More particularly, the present invention relates to a styrene resin composition which can be suitably used for automobile interior materials such as pillar and instrument panel of automobiles, housings of household electric appliances such as electronic jar rice cooker and electronic oven, housings of office automation equipments such as telephone and facsimile machine, and others such as sundry goods, and to a rubber-containing resin composition used for preparing the styrene resin composition.
In order to improve mechanical properties such as impact resistance and properties such as surface appearance of rubber-modified styrene resins, it is known to mix a matrix of a styrene resin with an ABS resin having a high rubber content which comprises as a main component a graft copolymer wherein at least one monomer is graft-polymerized onto a rubber, in the form of a latex or a slurry. The graft copolymer can be uniformly dispersed into the styrene resin in this manner.
Also, in recent years, a process has been investigated for preparing a desired rubber-modified styrene resin by incorporating a powder of the high rubber content ABS resin into pellets or beads of the styrene resin matrix, from the viewpoints of productivity of rubber-modified styrene resins and convenience in control for producing various grades of the resins. However, this process has the disadvantage that when a powder of high rubber content ABS resin having a rubber content of about 40-80% by weight is used, the obtained rubber-modified styrene resins have impaired properties such as impact resistance, surface appearance and heat stability, since the styrene resin and the ABS resin must be melt-mixed at a high temperature in order to uniformly disperse the graft copolymer (ABS resin) into the styrene resin.
In order to eliminate this disadvantage, it is proposed to incorporate a polymer of an acrylic acid ester, a methacrylic acid ester or styrene to raise the dispersibility of the high rubber content ABS resin, thereby lowering the mixing temperature, as known from Japanese Patent Publication Kokai No. 57-5755. However, this proposal has the disadvantage that the impact resistance and heat resistance of the obtained rubber-modified styrene resin are impaired.
It is an object of the present invention to provide a rubber-modified styrene resin which can provide molded articles having excellent properties such as impact resistance, tensile strength, elongation, heat resistance, molding processability and surface appearance, in particular excellent impact resistance and surface appearance.
A further object of the present invention is to provide a rubber-containing resin composition suitable for incorporating into styrene resins to prepare a rubber-modified styrene resin having improved properties.
A still further object of the present invention is to provide a styrene resin composition containing the rubber-containing resin composition and having improved properties as mentioned above.
These and other objects of the present invention will become apparent from the description hereinafter.